[Hat] Thoughts, Int vs Integer

[Thomas Davie]

On 24 Jun 2006, at 21:11, Neil Mitchell wrote:

> Hi,
>
>> > 1) big_number * 2 will never overflow, which will give a different
>> > semantics. Personally this sounds like a good idea, and having a
>> > hat-overflow tool to detect when an Integer goes above 2^31 would
>> > probably be a useful addition. I don't consider this change to  
>> be all
>> > that bad, since its compatible with the Haskell98 report (I think).
>>
>> The basic problem with this is that the bug may well be that an Int
>> is overflowing... You don't want the bug to not manifest it's self in
>> the self tracing version.
>
> If we assume that most Haskell numbers are below 2 billion - both Int
> and Integer, then its easy enought to detect all the places where a
> number exceeds this in the trace. I suspect that for most programs
> this will be never. If it does occur, I suspect it will be very rare,
> and all these occurences can be listed, which would directly track
> down the bug really quickly (faster than with the current Hat tools).
> The theoretical "hat-overflow" tool can be written which does this.

I think the question is more whether such a tool would ever be run.   
The users thought path is likely to be along the lines of "oh... it  
works now... I can't debug it if it worked"

Bob